Upper Respiratory Tract Infection

CHRIS B. DEL MAR, M.D., and PAUL GLASZIOU, PH.D., University of Queensland, Brisbane, Australia

Questions Addressed

• What are the effects of treatments for upper respiratory tract infections?

Summary of Interventions Beneficial Antibiotics for preventing (rare) complications of beta hemolytic streptococcal pharyngitis Analgesia/anti-inflammatories for symptom relief Likely to be beneficial Antibiotics for decreasing time to recovery in people with proven infection with Haemophilus influenzae, Moraxella catarrhalis, or Streptococcus pneumoniae Beta agonists for reducing duration of cough Vitamin C Zinc intranasal gel for reducing the duration of cold symptoms Decongestants for short- term relief of congestive symptoms Antihistamines Trade off Antibiotics for reducing time to recovery in people with acute bronchitis, pharyngitis, and sinusitis Unknown effectiveness Zinc lozenges Echinacea for treatment Echinacea for prevention Steam inhalation Ineffective or harmful Antibiotics in people with colds, coughs, and sore throat Decongestants for long-term relief of congestive symptoms

Definition Upper respiratory tract infection involves inflammation of the respiratory mucosa from the nose to the lower respiratory tree, not including the alveoli. In addition to malaise, it causes localized symptoms that constitute several overlapping syndromes: sore throat (pharyngitis), rhinorrhea (common cold), facial fullness and pain (sinusitis), and cough (bronchitis).

Incidence/Prevalence Each year, the average child will have about five such infections and the average adult will have two to three infections.¹

Etiology/Risk Factors Infective agents include more than 200 viruses (with 100 rhinoviruses) and several bacteria. Transmission is mostly through hand-to-hand contact with subsequent passage to the nostrils or eyes rather than, as commonly perceived, through droplets in the air.²

Prognosis Upper respiratory tract infections are usually self-limiting. Although they cause little mortality or serious morbidity, upper respiratory tract infections are responsible for considerable discomfort, lost work, and medical costs. Clinical patterns vary and overlap between infective agents. In addition to nasal symptoms, one half of sufferers experience sore throat and 40 percent experience cough. Symptoms peak within one to three days and generally clear by one week, although cough often persists.²

Clinical Aims To relieve symptoms and to prevent suppurative and nonsuppurative complications of bacterial infection, with minimal adverse effects from treatments.

Clinical Outcome Cure rate; duration of symptoms; incidence of complications; incidence of adverse effects of treatment.

Evidence-Based Medicine Findings

SEARCH DATE: CLINICAL EVIDENCEUPDATE SEARCH AND APPRAISAL
OCTOBER 2001

Antibiotics

We found no evidence that antibiotics have a clinically important effect on colds. Systematic reviews have found a minimal to modest effect of antibiotics in people with acute bronchitis, sore throat, and sinusitis. Antibiotics can prevent nonsuppurative complications of beta hemolytic streptococcal pharyngitis, but in industrialized countries such complications are rare.

Beta Agonists

Two randomized controlled trials (RCTs) have found that beta agonists reduce the duration of cough in acute bronchitis compared with placebo or erythromycin, although limited evidence from a third RCT suggests that this beneficial effect may occur only in people with bronchial hyperresponsiveness, wheeze, or airflow limitation.

Vitamin C

One systematic review has found evidence that vitamin C reduces the duration of symptoms in people with upper respiratory tract infections. However, the beneficial effect is small and may be explained by publication bias.

Zinc

Two systematic reviews found no clear evidence that zinc gluconate or acetate lozenges are beneficial in people with upper respiratory tract infections. Two RCTs have found conflicting evidence about effects of zinc nasal gel on duration of symptoms.

Echinacea

Systematic reviews found limited evidence that some preparations of echinacea may be better than placebo for treatment and prevention of colds, but we found insufficient evidence about effects of a specific echinacea product compared with other or no interventions for treating or preventing common colds.

Steam Inhalation

One systematic review found conflicting evidence for the efficacy of steam inhalation.

Decongestants

One systematic review found evidence for limited short-term benefit following a single dose but no evidence of benefit with longer use of decongestants for symptomatic relief.

Antihistamines

One systematic review has found evidence that antihistamines produce small clinical benefits for the symptoms of runny nose and sneezing.

Analgesic and Anti-inflammatory Agents

One systematic review has found that analgesic and anti-inflammatory agents significantly relieve the symptoms of sore throat. One RCT has found that steroid spray provides additional benefit to antibiotics for acute sinusitis.

Adapted with permission from Del Mar CB, Glasziou P. Upper respiratory tract infection. Clin Evid 2002;7:1391-9.

REFERENCES

1. Fry J, Sandler G. Common diseases. Their nature prevalence and care. Dordrecht, The Netherlands: Kluwer Academic, 1993.
2. Lauber B. The common cold. J Gen Intern Med 1996;11:229-36.

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